Laser delivery device and ion trap system

Abstract

This application discloses a laser transmission device and an ion trap system. The laser transmission device, applied in an ion trap system, includes a spatial mode converter and a diffraction element array, which are located on different planes in space. The spatial mode converter is used to irradiate multiple laser beams onto the diffraction element array. The diffraction element array is used to independently irradiate the corresponding ions with each laser beam, resulting in a non-parallel laser beam emitted perpendicular to the ion chain direction after passing through the diffraction elements. In this design, since the diffraction element array is not coplanar with the spatial mode converter, its arrangement and number are not limited by the spatial mode converter, making it easily expandable. Furthermore, the non-coplanar design eliminates the need for direct coupling between the optical fiber and the chip, avoiding the limitation imposed by chip size on the number of optical fibers. The arrangement of the diffraction element array helps to increase the numerical aperture of the diffraction elements, enhance their focusing ability, output high-quality focused small spots, and reduce crosstalk.

Description

Technical Field

[0001] This application relates to the field of quantum computing technology, and in particular to a laser transmission device and an ion trap system. Background Technology

[0002] With the development of information technology, quantum computing has attracted increasing attention. The unique aspect of quantum computing lies in the superposition property of quantum states, which makes large-scale "parallel" computing possible. This is because the fundamental principle of quantum computing is to encode information using qubits (i.e., ions). A single qubit can exist not only in the two classical states of 0 and 1, but also in a superposition of 0 and 1 (e.g., 0 qubit 1 qubit 2 qubit 3 qubit 4 qubit 5 qubit 6 qubit 7 qubit 8 qubit 9 qubit 1 qubit 1 qubit 1 qubit 1 qubit 1 qubit 1 qubit 2 ... Figure 1 As shown, a qubit can be in a state with a 50% probability of being in state 0 and a 50% probability of being in state 1. n qubits can simultaneously be in a state 2. n A quantum state is a superposition of quantum states. Different quantum algorithms perform different quantum operations on different numbers of qubits. The more qubits there are, the stronger their parallel acceleration capability, and the faster they can solve the same problem.

[0003] In terms of the physical realization of quantum computers, the current mainstream international approach is to use ion trap systems or superconducting systems. The basic process of quantum computing using an ion trap system is as follows: heated atoms are ionized to form ions; in a vacuum cavity, alternating radio frequency and DC electric fields generated by an ion trap integrated chip trap the ions into ion chains; the ions, cooled by cooling light, interact with manipulation light emitted from the ion trap integrated chip to reach a specific quantum state; and quantum computing is achieved by manipulating this quantum state.

[0004] In multi-ion scenarios, the manipulation of ion quantum states is achieved by independently directing control light onto different ions. This manipulation is accomplished by independently focusing lasers (arrows) targeting different ions; the detection of quantum states is achieved through imaging optical paths and fluorescence readout using CCDs, PMTs, etc. Quantum gate operations are completed by controlling the duration of the control laser through an external timing control unit.

[0005] However, current ion trap systems are limited by the size and arrangement of optical elements, making it difficult to achieve small spot focusing and to extend the scale of long ion chains, thus affecting the computing power of quantum computers. Summary of the Invention

[0006] This application provides a laser transmission device and an ion trap system, which can solve the problem that the number of ions in an ion trap system is not easily expanded.

[0007] In a first aspect, embodiments of this application provide a laser transmission device applied in an ion trap system. Specifically, the device includes a spatial mode converter and a diffraction element array, which are located on different planes in space. The spatial mode converter is used to irradiate multiple laser beams onto the diffraction element array. The diffraction element array is used to independently irradiate the multiple laser beams onto corresponding ions, and some of the laser beams are not parallel to each other after passing through a row of diffraction elements perpendicular to the ion chain direction in the diffraction element array. Each laser beam after passing through the diffraction element array corresponds to one ion in the ion chain, where the ion chain is a one-dimensional long chain comprising multiple ions.

[0008] In traditional ion trap systems, optical fibers are directly coupled to the chip, and waveguides and diffraction elements are all mounted on the chip. Due to limitations in arrangement and chip size, it is difficult to increase the number of optical fibers and diffraction elements. However, in the solution described in this application, the diffraction elements are first arranged in a two-dimensional array, and the spatial mode converter is placed on a different plane from the diffraction element array. Therefore, if the diffraction element array is still placed on the chip, the spatial mode converter is located outside the chip, thus significantly increasing the number of diffraction elements. Furthermore, since the spatial mode converter is located outside the chip, the optical fiber used to provide the laser source, whether directly coupled to the spatial mode converter or not, does not need to be directly coupled to the chip, thus avoiding the limitation imposed by chip size on the number of optical fibers. Because the above device significantly reduces the limitations on the number of optical fibers and diffraction elements, it is possible to achieve a greater number of independent lasers to irradiate ions in the ion chain separately, thereby increasing the number of ions in the ion trap system and improving the computational power of quantum computing. On the other hand, the arrangement of diffraction element arrays is beneficial to increasing the numerical aperture of the diffraction elements, increasing the focusing ability of the diffraction elements, outputting high-quality focused small light spots, and reducing crosstalk.

[0009] In one possible implementation, the device further includes a collimator array for collimating the multiple laser beams provided by the fiber array. The collimator array is located between the fiber array and the spatial mode converter, ensuring that the collimated laser beams can illuminate the spatial mode converter. Collimating the laser improves its focusing effect. This is especially beneficial for lasers with large diffraction angles after passing through diffraction elements, as large diffraction angles reduce beam quality; collimation improves the beam quality when irradiating ions.

[0010] In one possible implementation, the diffraction element is a metasurface structure formed by multiple micro / nano units fabricated from a dielectric material. The metasurface structure allows for flexible and effective control of electromagnetic wave polarization, amplitude, phase, polarization mode, and propagation mode, making it easier to control laser light irradiated onto the ion chain.

[0011] In one possible implementation, adjacent diffraction elements along the direction parallel to the ion chain share a common micro / nano unit within the diffraction element array. This shared micro / nano unit allows for a more compact arrangement of the diffraction element array, further increasing the number of diffraction elements. Both adjacent laser beams along the ion chain will irradiate the shared micro / nano unit; however, due to the metasurface structure of the diffraction elements, the polarization of the laser beams can be controlled. By setting the two laser beams to different polarizations, the emission directions of the two laser beams irradiating the shared micro / nano unit will be inconsistent, thus irradiating the corresponding ions.

[0012] In one possible implementation, the collimator array consists of multiple collimating lenses with different focal lengths along the direction perpendicular to the ion chain. After a laser beam passes through a series of diffraction elements, the diffraction angles vary. A larger diffraction angle reduces the quality of the emitted laser spot. Therefore, by setting a larger focal length for the collimating lenses, the focusing ability of the lenses can be enhanced, improving the quality of the emitted laser spot and thus compensating for the reduced spot quality caused by greater diffraction after passing through the diffraction elements.

[0013] In one possible implementation, the collimator array includes either a grating coupler array or an end-face coupler array. The grating coupler or end-face coupler couples to the optical fiber allow the laser propagating in the fiber to continue propagating along the grating coupler or end-face coupler, which improves laser coupling efficiency and reduces laser energy loss.

[0014] In one possible implementation, the spatial mode converter comprises multiple confocal lenses; alternatively, the spatial mode converter is an optical waveguide array. At least two confocal lenses or lens groups enable "scaling" of the laser, matching the emitted laser array with the diffraction element array. The optical waveguide array guides the light waves through it, with each waveguide corresponding to a diffraction element, thereby transmitting the laser array to the corresponding diffraction element array.

[0015] In one possible implementation, the optical waveguide is a tapered waveguide. The tapered waveguide facilitates an increase in mode size and a reduction in the output divergence angle, thereby achieving amplitude and phase matching with the diffractive optical element.

[0016] In one possible implementation, the tapered waveguide is an arc-shaped slope structure. The arc-shaped slope structure of the tapered waveguide allows for smoother mode transitions, effectively reduces the influence of diffraction effects, and decreases the required length of the tapered region.

[0017] In one possible implementation, the device further includes a rectangular waveguide array for transmitting the multiple laser beams to the spatial mode converter. The rectangular waveguide array can be positioned between the collimator array and the spatial mode converter to achieve laser array transmission; if the laser transmission device does not include a collimator array, the rectangular waveguide array can be positioned between the fiber array and the spatial mode converter to achieve laser array transmission.

[0018] In one possible implementation, the device is located in a vacuum cavity. Placing the optics in a vacuum cavity effectively avoids multi-stage amplification of the light beam, reduces the size of the light spot, and thus helps to reduce the size of the ion trap system.

[0019] Secondly, embodiments of this application provide an ion trap system, including an optical fiber array and a laser transmission device as described in the first aspect or any one of the claims, wherein a plurality of optical fibers in the optical fiber array correspond one-to-one with a plurality of diffraction elements in the diffraction element array. This ion system significantly reduces the limitations on the number of optical fibers and diffraction elements, thereby enabling a greater number of independent lasers to irradiate ions on the ion chain separately, thus increasing the number of ions in the ion trap system and improving the computational power of quantum computing. Furthermore, the arrangement of the diffraction element array is beneficial for increasing the numerical aperture of the diffraction elements, increasing their focusing ability, outputting a high-quality focused small spot, and reducing crosstalk.

[0020] In one possible implementation, the aforementioned optical fiber is a thermally expanded core fiber. When the numerical aperture of the diffraction element gradually increases from the center to both sides, and / or the focal length of the collimating lens gradually increases from the center to both sides, using TEC fiber can achieve a higher quality emitted laser that matches the diffraction element. Attached Figure Description

[0021] Figure 1 A schematic diagram of the principle of a quantum bit is provided for the embodiments of this application;

[0022] Figure 2 A schematic diagram of a conventional ion trap system structure provided in this application embodiment;

[0023] Figure 3a and Figure 3b This is a schematic diagram of another conventional ion trap system structure provided in an embodiment of this application;

[0024] Figure 4 Provided for the embodiments of this application Figure 3a Enlarged schematic diagram of the middle region D';

[0025] Figure 5 The embodiments provided in this application are based on Figure 3a and Figure 3bThe diagram shows the structure of the ion trap system with a multi-ion arrangement.

[0026] Figure 6 This is a schematic diagram of a laser transmission device provided in an embodiment of this application;

[0027] Figure 7 A schematic diagram of the arrangement of the diffraction element array provided in the embodiments of this application;

[0028] Figure 8 This is a schematic diagram of another laser transmission device structure provided in an embodiment of this application;

[0029] Figure 9a This is a schematic diagram of a grating coupler array provided in an embodiment of this application;

[0030] Figure 9b This is a schematic diagram of an end-face coupler array provided in an embodiment of this application;

[0031] Figure 10 A schematic diagram showing that the two diffraction elements provided in the embodiments of this application share a common micro / nano unit;

[0032] Figure 11a This is a schematic diagram of the structure of the tapered optical waveguide provided in the embodiments of this application;

[0033] Figure 11b A schematic diagram illustrating the matching of an optical waveguide and a diffractive optical element array provided in an embodiment of this application;

[0034] Figure 12 This is a schematic diagram of the structure of a laser transmission device in a specific embodiment of this application.

[0035] Figure 13 The embodiments provided in this application are based on Figure 12 The diagram shows the spot effect of the laser transmission device.

[0036] Figure 14a This is a schematic diagram of the structure of the laser transmission device in another specific embodiment provided in this application.

[0037] Figure 14b A schematic diagram of the structure of the laser transmission device in another specific embodiment provided in this application;

[0038] Figure 15 The embodiments provided in this application are based on Figure 14a The diagram shows the spot effect of the laser transmission device.

[0039] Figure 16 This is a schematic diagram of an ion trap system provided in an embodiment of this application. Detailed Implementation

[0040] exist Figure 2 In one ion trap system illustrated, conventional optical elements are used for focusing and addressing. Specifically, N ions are trapped in a one-dimensional chain in a vacuum. The manipulation light is split into two paths: a global Raman beam and individual Raman beams. Each individual Raman beam needs to be aligned with a single ion, i.e., independent addressing. After being split by a beam splitter, the individual Raman beams are modulated by a multi-channel acousto-optic modulator and then focused by a lens with a large numerical aperture (NA) to precisely hit the ion chain. The modulator controls the switching and frequency of the light, enabling manipulation of the ion quantum state. However, the field of view of the aberration-correcting lens group composed of conventional optical lenses is limited, resulting in a limited number of individual Raman beams for addressing and poor scalability. Furthermore, the multi-stage amplification of the beam reduces the size of the ion trap quantum computer to the order of meters.

[0041] Figure 3a and Figure 3b These are top and side views of another ion trap system, respectively. Figure 3a As shown, both radio frequency electrodes 01 and DC electrode 02 are connected to a power source. After power is applied, radio frequency electrode 01 can generate an alternating radio frequency electric field, and DC electrode 02 can generate a DC electric field. The radio frequency electric field and the DC electric field work together to generate a trapping potential well for trapping ions. Figure 3b for Figure 3a The ion trap integrated chip 001 is shown as a side view at point B'-B'. The ion trap integrated chip 001 is connected to optical fiber 002, which transmits manipulating light of a specific frequency and polarization. The manipulating light is coupled from optical fiber 002 into the ion trap integrated chip 001, transmitted through waveguide 03, and then coupled to the grating region C'. The focused integrated beam strikes the trapped ions, achieving quantum state manipulation.

[0042] Figure 4 for Figure 3a An enlarged schematic diagram of the central region D'. (See attached diagram.) Figure 4 As shown, spheres 1 and 2 represent two ions in the example. Figure 4 Each grating 04 corresponds to one ion. Figure 5 For based on Figure 3a and Figure 3b The diagram shows a top view of the multi-ion arrangement implemented by the ion trap integrated chip 001. For example, the number of ions and the number of gratings 04 are both 5. Combined with... Figure 3a , Figure 3b , Figure 4 and Figure 5 As can be seen, the optical fiber is directly coupled to the chip, and the waveguide and diffraction elements are all set on the chip. Due to the limitations of the arrangement of the waveguide and diffraction elements, as well as the chip size, the number of diffraction elements that can be set on the chip is limited, and the number of optical fibers that can be coupled to the chip is limited. This limits the number of ions in the ion trap and reduces the computing power of the quantum computing system in which the ion trap is located.

[0043] In view of this, embodiments of this application provide a laser transmission device that can be applied to an ion trap system to solve the problem that the number of diffraction elements is not easily expanded, thereby realizing the expansion of the number of ions in the ion trap system.

[0044] Figure 6 The figure shows a schematic diagram of the structure of the laser transmission device provided in the embodiment of this application. The laser transmission device provided in the embodiment of this application includes a spatial mode converter 61 and a diffraction element array 62, and the spatial mode converter 61 and the diffraction element array 62 are located on different planes in space.

[0045] Laser after passing through such Figure 6 In the laser transmission device shown, the laser first passes through a spatial mode converter 61 in the Z-axis direction, and then through a diffraction element array 62. The spatial mode converter 61 and the diffraction element array 62 are located on different spatial planes; specifically, they are not located on the same XOY plane, meaning their Z coordinates are different. Furthermore, although in Figure 6 The spatial modulus converter 61 and the diffraction element array 62 are located on mutually parallel XOY planes, but in some embodiments, their planes may not be parallel. It should be understood that the fact that the spatial modulus converter 61 and the diffraction element array 62 are located on different planes in space does not constitute a limitation on the length of the device in the Z-axis direction.

[0046] Specifically, the spatial mode converter 61 is used to irradiate the diffraction element array with multiple laser beams, so that each laser beam irradiates one diffraction element of the diffraction element array 62. For example, the size of the fiber array is usually larger than the size of the diffraction element array. Therefore, the spatial mode converter 61 can be used to scale the multiple laser beams as a whole, so that each laser beam irradiates the corresponding diffraction element.

[0047] The diffraction element array 62 is used to independently irradiate corresponding ions in the ion chain with multiple laser beams, thereby achieving quantum state manipulation. The diffraction element array 62 includes a plurality of diffraction elements. In one specific embodiment, the diffraction element array 62 can be arranged as follows: Figure 7 As shown, each laser beam irradiates a diffraction element, and each diffraction element corresponds to an ion, thereby enabling multiple laser beams to irradiate each ion in the ion chain. Figure 7 The examples 'a' and 'b' in the diagram provide two exemplary arrangements of the diffraction element array 62. However, in practical applications, the arrangement of the diffraction element array 62 is not limited to these and can also be other arrangements. Furthermore, Figure 7 The number of rows and columns of diffraction elements in the diffraction element array 62 is merely an example and is not limited in this application.

[0048] An ionic chain is a one-dimensional long chain consisting of several ions. Figure 6 In the embodiment shown, the one-dimensional ion chain lies on a straight line parallel to the X-axis (due to...). Figure 6 The X-axis is perpendicular to the plane of the paper, therefore the ion chains are in... Figure 6 (Only one ion is displayed in the image). The diffraction element array 62 is arranged on a plane parallel to the XOY plane. Since the multiple laser beams passing through the diffraction element array 62 need to independently irradiate the corresponding ions in the ion chain, the laser beams emitted after passing through a row of diffraction elements in the diffraction element array 62 along the direction perpendicular to the ion chain (along the Y-axis) are not parallel to each other. Figure 6 In the embodiment shown, the ion chain is located in the middle of the diffraction element array 62 in the Y-axis direction. Therefore, the laser has a smaller diffraction angle after passing through the diffraction element in the middle of the diffraction element array 62 in the Y-axis direction; while the laser has a larger diffraction angle after passing through the diffraction elements on both sides of the diffraction element array 62 in the Y-axis direction.

[0049] In the above embodiments, since the spatial mode converter 61 and the diffraction element array 62 are located on different planes in space, the spatial mode converter 61 does not affect the arrangement of the diffraction elements. If the diffraction element array 62 is placed on the chip, the spatial mode converter 61 is located outside the chip, and the spatial mode converter 61 does not need to occupy the limited space on the chip, which is beneficial for increasing the number of diffraction elements. In addition, since the spatial mode converter 61 is located outside the chip, the optical fiber used to provide the laser source, whether directly coupled to the spatial mode converter or not, does not need to be directly coupled to the chip, thereby avoiding the limitation of chip size on the number of optical fibers.

[0050] On the other hand, since the diffraction elements are arranged in an array, see Figure 7 If the five diffraction elements in the first column correspond to ions 1-5 on the ion chain from top to bottom, and the five diffraction elements in the second column correspond to ions 6-10 on the ion chain from top to bottom, then the first and second diffraction elements in the first row correspond to ions 1 and 6 on the ion chain, respectively. Therefore, the diameter of each diffraction element can be set to 5d, where d represents the inter-ion spacing. Figure 7 Taking the diffraction element array 62 with 5 diffraction elements per column as an example, if each column includes N diffraction elements, the radius of the diffraction elements can be set to N*d. Therefore, the above embodiment is beneficial for increasing the numerical aperture of the diffraction elements, thereby helping to increase the focusing ability of the diffraction elements and output a high-quality focused small spot. In addition, the diffraction element array has no spatial overlap and adopts an off-axis design, that is, the beams perpendicular to the ion chain direction are not parallel to each other, resulting in low crosstalk between channels.

[0051] Because the above-mentioned device significantly reduces the limitations on the number of optical fibers and diffraction elements, it enables a greater number of independent lasers to irradiate ions on the ion chain separately, thereby increasing the number of ions in the ion trap system and improving the computing power of quantum computing. In addition, it can also irradiate the ion chain with high-quality focused small light spots, improving the performance of the quantum computing system.

[0052] Furthermore, the aforementioned laser transmission device can also be as follows: Figure 8 As shown, it also includes a collimator array 63. The collimator array 63 is used to collimate the multiple laser beams transmitted through the fiber optic array and then directs the collimated laser beams onto the spatial mode converter 61. The collimator array 63 can collimate the laser beams and adjust the size of the output beam spot, which helps to improve the focusing effect of the laser beams.

[0053] The collimator array 63 contains multiple collimators that correspond one-to-one with the diffraction elements in the diffraction element array 62. That is, after passing through a collimator, a laser beam is irradiated by the corresponding diffraction element in the diffraction element array 62 through the spatial mode converter 61, and then irradiates the corresponding ion. Furthermore, the collimators in the collimator array 63 also correspond one-to-one with the multiple optical fibers in the fiber array. That is, each optical fiber corresponds to one collimator, each collimator corresponds to one diffraction element, and each diffraction element corresponds to one ion. Therefore, each laser beam will be irradiated by its corresponding ion.

[0054] In one possible design, the collimator array 63 can be composed of a collimating lens array, with each collimating lens corresponding to an optical fiber in an optical fiber array, used to collimate the laser transmitted through that fiber. The focal length of the collimating lens array needs to be matched with the spatial mode converter 61. If a larger focal length of the collimating lens is required, the collimating lens can be omitted, allowing the optical fiber array to be directly coupled to the spatial mode converter 61.

[0055] The collimating lenses can also be arranged as follows: Figure 7 As shown. The collimating lens array can be arranged in the same way as the diffraction element array to facilitate the laser light passing through the collimating lens to be irradiated onto the corresponding diffraction element after passing through the spatial mode converter. The aperture of a collimating lens is usually larger than the aperture of a diffraction element, that is, the area occupied by the collimator array 63 is larger than the area occupied by the diffraction element array 62. If there is no spatial mode converter 61 between the collimator array 63 and the diffraction element array 62, it is impossible to independently irradiate the corresponding diffraction element with the multiple laser beams after passing through the collimator array 63. The spatial mode converter 61 scales the multiple laser beams as a whole, thereby irradiating each laser beam onto the corresponding diffraction element.

[0056] In a collimating lens array, the focal lengths of a row of collimating lenses (i.e., collimating lenses perpendicular to the ion chain direction) can vary. As mentioned earlier, the diffraction angles of a laser beam after passing through a row of diffraction elements differ. Taking the ion chain located in the middle of the diffraction element array 62 as an example, the laser beam has a smaller diffraction angle after passing through the diffraction element in the middle of the row; however, the laser beam has a larger diffraction angle after passing through the diffraction elements above and below the row. A larger diffraction angle reduces the quality of the emitted laser spot. Therefore, a collimating lens with a smaller focal length can be placed in the middle of the row, while collimating lenses with larger focal lengths can be placed above and below the row. The collimating lens with a larger focal length enhances the focusing ability of the lens, improves the quality of the emitted laser spot, and thus compensates for the reduced spot quality caused by greater diffraction after passing through the diffraction elements. Furthermore, setting different focal lengths can help reduce the complexity of the spatial mode converter. Especially when the diffraction elements in the diffraction element array are not exactly the same, the diffraction efficiency of the diffraction elements can be improved by adjusting the output spot size through different collimator focal lengths.

[0057] In another possible design, the collimator array 63 may also include a grating coupler array, such as Figure 9a As shown; alternatively, the collimator array 63 may also include an end-face coupler array, such as Figure 9b As shown. Figure 9a and Figure 9b The schematic diagram of one column of collimators in collimator array 63 is provided only as an example. As shown in the figure, grating couplers or end-face couplers are coupled to the optical fiber, allowing the laser propagating in the optical fiber to continue propagating along the grating couplers or end-face couplers. The grating couplers or end-face couplers also have a collimating effect on the laser. If collimator array 63 is a grating coupler array or an end-face coupler array, the laser emitted from the optical fiber array propagates along the medium in collimator array 63, which helps to improve the coupling efficiency of the laser and reduce laser energy loss.

[0058] Grating couplers can be on-chip grating couplers, achieving high coupling efficiency through reasonable grating parameter design and material selection. End-face couplers can employ the reciprocal structure of a three-dimensional conical mode converter, achieving high coupling efficiency through the use of an arc-shaped conical structure.

[0059] In one possible implementation, the diffraction elements in the aforementioned diffraction element array 62 can be metasurface structures formed by multiple micro / nano units fabricated from a dielectric material. For example, the diffraction elements can be superlenses of the metasurface structure, each superlens including several electromagnetic micro / nano units. These electromagnetic micro / nano units are located in various structures such as elliptical cylinders, ring cylinders, and polygonal cylinders, used to expand the focusing aperture and output a dense chain of focused light spots. The numerical apertures of the multiple superlenses in the closely arranged superlens array can be equal or unequal. As mentioned earlier, the diffraction angles of a column of superlenses perpendicular to the ion chain direction are different. Since a larger diffraction angle reduces the quality of the emitted laser spot, to compensate for the inconsistency in spot quality caused by the diffraction angle, superlenses with larger numerical apertures can be used for diffraction elements with larger diffraction angles to improve their focusing ability and enhance the quality of the emitted spot, while superlenses with smaller numerical apertures can be used for diffraction elements with smaller diffraction angles. Taking the ion chain located at the center of the diffraction element array 62 in the Y-axis direction as an example, the numerical aperture of the diffraction element array 62 gradually increases from the center to both sides in the Y-axis direction.

[0060] Since diffraction elements can be metasurface structures formed by multiple micro / nano units, in order to make the diffraction element array 62 more densely arranged and further increase the number of diffraction elements, adjacent diffraction elements along the direction parallel to the ion chain can share a common micro / nano unit. Figure 10 In the specific embodiment shown, each solid circle represents a diffraction element, and the shaded area represents a shared micro / nano unit. It should be understood that... Figure 10 This is just one specific example; in practical applications, the proportion of micro / nano units that two diffraction elements can share can be greater than that of micro / nano units. Figure 10 The diagram shows more or less. Because the diffraction elements of the metasurface structure can control the polarization and wavelength of laser light, adjacent laser beams parallel to the ion chain direction can be set to different polarizations or wavelengths. This allows two laser beams to irradiate a shared micro / nano unit, but because the metasurface structure's micro / nano unit can control polarization and wavelength, the laser beams with different polarizations or wavelengths will exit in different directions, thus irradiating different ions. For example, different types of ions may have different wavelength requirements for controlling the laser. If different types of ions exist in the ion chain, different wavelengths can be activated, satisfying both the need for ion manipulation and enabling multiple laser beams to exit in different directions when irradiating a shared micro / nano unit.

[0061] To improve the focusing effect of the laser irradiating the ions, the distance between the ion chain and the diffraction element array (e.g., ...) can be increased. Figure 6 , Figure 8The distance shown on the Z-axis is set as the focal length of the diffraction element, so that the laser can be focused on the ions.

[0062] In one possible implementation, the spatial mode converter 61 described above can be multiple confocal lenses. Specifically, the spatial mode converter 61 may include at least two confocal lenses or lens groups to "scale" the laser so that the emitted laser array matches the diffraction element array 63.

[0063] In another possible implementation, the aforementioned spatial mode converter 61 can also be an optical waveguide array. An optical waveguide is a dielectric device that guides light waves to propagate; it is also called a dielectric optical waveguide. An optical waveguide array can be used to transmit laser arrays and realize the spacing conversion from the collimator array 63 to the diffraction element array 62, or from the fiber array to the diffraction element array 62. When the laser transmission device includes the collimator array 63, each optical waveguide is coupled to one collimator and transmits the collimated laser to a corresponding diffraction element. When the laser transmission device does not include the collimator array 63, the spatial mode converter 61 can be directly coupled to the fiber array, i.e., each optical waveguide is coupled to one fiber and transmits the laser to a corresponding diffraction element.

[0064] Each optical waveguide in the optical waveguide array can be a tapered waveguide. Tapered waveguides facilitate increasing the mode size and reducing the output divergence angle, thereby achieving amplitude and phase matching with diffractive optical elements. Furthermore, the tapered waveguides can be implemented using an on-chip three-dimensional tapered waveguide scheme, such as... Figure 11a As shown, the darker areas represent the optical waveguide, and the lighter areas represent the dielectric material. The structure of the optical waveguide includes the input single-mode waveguide (coupled to the collimator, i.e.,...) Figure 11a The system comprises a dark, slender, elongated section at the front end, a symmetrical horizontal tapered transducer that extends the mode width, an on-chip vertical tapered transducer that extends the mode height, and a final output waveguide (used to output the laser spot to the ion chain). Furthermore, the tapered slope can be an arc surface, making the mode transition smoother, effectively reducing the influence of diffraction effects and decreasing the required length of the tapered region. Figure 11b The matching structure of the tapered waveguide and the diffractive optical element array in this embodiment is further illustrated. Figure 11b Taking a 2x2 configuration as an example, the lasers transmitted in the two horizontal waveguides (parallel to the ion chain direction) have different polarizations, denoted as TE and TM respectively. Therefore, although their corresponding diffraction elements share a common part, which is irradiated by the lasers transmitted in the two waveguides, the superlens has a modulating effect on the polarization of the light. Thus, after passing through the common part, the lasers with different polarizations will be emitted in different directions, thereby irradiating the corresponding ions.

[0065] Optionally, the laser transmission device may further include a rectangular waveguide array or other shaped waveguide array, disposed between the collimator array 63 and the spatial mode converter 61, for transmitting the laser array; if the laser transmission device does not include the collimator array 63, the rectangular waveguide array may be disposed between the fiber array and the spatial mode converter 61 for transmitting the laser array.

[0066] To further improve the laser spot quality, the aforementioned laser transmission devices can all be housed within a vacuum cavity. Figure 2 In the conventional ion trap system shown, since the optical components are all located outside the vacuum cavity, multi-stage amplification of the light beam is unavoidable, resulting in the size of the ion trap quantum computer reaching the meter level. However, in the embodiments of this application, the optical components can be placed inside the vacuum cavity, effectively avoiding multi-stage amplification of the light beam, reducing the size of the light spot, and thus helping to reduce the size of the ion trap system.

[0067] To better understand the above embodiments of this application, the following examples are provided in conjunction with the accompanying drawings.

[0068] See Figure 12 This is a specific embodiment provided in this application. Figure 12 In the specific embodiment shown, the laser transmission device includes a collimator array 63, a spatial mode converter 61, and a diffraction element array 62, all located within the vacuum cavity of the ion trap system. The collimator array 63 is a collimating lens array; each fiber in the fiber array transmits the laser to a corresponding collimating lens in the collimating lens array. The collimating lens collimates the laser and transmits it to the spatial mode converter 61. The spatial mode converter 61 includes two confocal lenses (groups) used to irradiate the laser array onto the corresponding diffraction element array 62. The diffraction element array 62 is a superlens array, where the superlenses do not share any micro / nano units. A single laser beam (arranged perpendicular to the ion chain direction) in the laser array, after passing through its corresponding superlens (arranged perpendicular to the ion chain direction) in the superlens array, becomes non-parallel, ensuring that each laser beam irradiates the corresponding ion in the one-dimensional ion chain.

[0069] Figure 12 The diagram shows a cross-sectional view of the laser transmission device in the YOZ plane. In this cross-section, the collimator array 63 can only display one column of collimators, and the diffraction element array 62 can only display one column of diffraction elements. The diagram uses an example where each column contains 5 collimators and 5 diffraction elements. In practical applications, each column can be configured to have more than [a certain number of elements]. Figure 12More or fewer collimators and diffraction elements. It should be understood that several rows of collimators and a corresponding number of diffraction elements can be arranged in a direction perpendicular to the plane of the paper. For example, the arrangement of fiber arrays, collimator arrays 63, and diffraction element arrays parallel to the YOZ plane can be as follows: Figure 7 As shown. Similarly, since the ion chains are also located in a direction perpendicular to the paper plane, therefore, Figure 12 Only one ion can be displayed at a time. A laser beam passes through a series of diffraction elements and then illuminates different ions in a chain of ions.

[0070] based on Figure 12 The specific embodiments shown were subjected to simulation calculations. Taking an array consisting of 2 rows and 2 columns as an example, the simulation experimental data of the laser spot output by the diffraction element array for ion manipulation can be obtained as follows: Figure 13 As shown in Tables 1 and 2.

[0071] Table 1

[0072]

[0073] Table 2

[0074]

[0075] according to Figure 13 As can be seen, the final output spot size is small, and the focusing effect is good. Table 1 above shows the coupling efficiency and crosstalk matrix of each laser path. As shown in Table 1, the coupling efficiency of each channel is above 50%, which significantly improves the coupling efficiency and reduces the crosstalk between channels compared with the traditional ion trap system.

[0076] See Figure 14a and Figure 14b This is another specific embodiment provided in this application. Figure 14a and Figure 14b In the specific embodiment shown, the laser transmission device includes a collimator array 63, a spatial mode converter 61, and a diffraction element array 62, all located in the vacuum cavity of the ion trap system. Figure 14a In the collimator array 63, a grating coupler array is used, with each grating coupler coupled to an optical fiber in the fiber array, transmitting the laser to the spatial mode converter 61; Figure 14bIn this configuration, the collimator array 63 serves as an end-face coupler, with each end-face coupler coupled to one fiber in the fiber array, transmitting the laser beam to the spatial mode converter 61. The end-face coupler 61 includes an optical waveguide array, used to direct the laser beam transmitted from the grating coupler array (or end-face coupler array) onto a corresponding diffraction element array 62. The diffraction element array 62 is a superlens array, where adjacent superlenses along the direction parallel to the ion chain share common micro / nano units. A single laser beam (arranged perpendicular to the ion chain direction) in the laser array, after passing through its corresponding superlens (arranged perpendicular to the ion chain direction) in the superlens array, becomes non-parallel, ensuring that each laser beam irradiates the corresponding ion in the one-dimensional ion chain.

[0077] Figure 14a and Figure 14b The diagram shown is a cross-sectional view of the laser transmission device on the XOY plane. On this cross-section, the collimator array 63 can only display one row of grating couplers or one row of end-face couplers, the spatial mode converter 61 can only display one row of optical waveguides, and the diffraction element array can only display one row of diffraction elements. It should be understood that in a direction perpendicular to the plane of the paper, several rows of grating couplers (or end-face couplers), a corresponding number of rows of optical waveguides, and a corresponding number of rows of diffraction elements can also be arranged.

[0078] based on Figure 14a The specific embodiments shown were simulated. Taking an array with 2 rows and 2 columns as an example, the experimental data of the laser spot output by the diffraction element array for ion manipulation can be obtained as follows: Figure 15 As shown in Tables 3 and 4.

[0079] Table 3

[0080]

[0081] Table 4

[0082]

[0083] according to Figure 15 As can be seen, the final output spot size is small, and the focusing effect is good. Table 3 above shows the coupling efficiency and crosstalk matrix of each laser path. As shown in Table 3, the coupling efficiency of each channel is above 50%, which significantly improves the coupling efficiency and reduces the crosstalk between channels compared with the traditional ion trap system.

[0084] Based on the same technical concept, embodiments of this application also provide an ion trap system, which may include an optical fiber array and the laser transmission device in any of the foregoing embodiments.

[0085] In one possible implementation, the optical fibers in the aforementioned fiber array can be thermally expanded core (TEC) fibers. Especially when the numerical aperture of the diffraction element gradually increases from the center outwards, and / or the focal length of the collimating lens gradually increases from the center outwards, using TEC fibers can achieve higher quality emitted laser light that matches the diffraction element.

[0086] Figure 16 An ion trap system is provided as an example, as shown in the figure. The ion trap system includes a vacuum system 16-1, a laser system 16-2, a trapping electromagnetic field generating device 16-3, a detection device 1-4, and a control system 1-5. The laser system 16-2 includes the laser transmission device 16-2-1 provided in the above embodiments of this application, which is disposed in the vacuum cavity O provided by the vacuum system 16-1.

[0087] Furthermore, the laser system 16-2 also includes manipulation light, detection light, and ionization, cooling, and pump light. The laser system 16-2 is connected to the ion trap integrated chip 100 via the laser transmission device 16-2-1. The trapping electromagnetic field generating device 16-3 is electrically connected to the ion trap integrated chip 100 to control the generation of a trapping potential. The detection device 16-4 consists of an imaging optical path, a charge-coupled device (CCD), and a photomultiplier tube (PMT), etc., to detect the quantum state of ions. The control system 16-5 generates timing and switching functions to control the other components. Specifically, the control system 1-5 is signal-connected to the laser system 1-2, the trapping electromagnetic field generating device 1-3, and the detection device 1-4, respectively.

[0088] The workflow of the aforementioned ion trap system is as follows: When the trapping electromagnetic field generator 1-3 is turned on, the ion trap integrated chip 100 provided in this embodiment is powered on in the vacuum cavity O. The alternating radio frequency electric field and DC electric field within the ion trap integrated chip 100 generate a trapping electromagnetic field. This trapping electromagnetic field traps ions (formed after the outer electrons of heated atoms are ionized) into ion chains. The ionized ions are trapped at a distance of tens of micrometers above the ion trap integrated chip 100. The cooling light and pump light in the laser system 16-2 cool and quantum initialize the ions, enabling them to reach a specific quantum state. Then, the ions are sideband cooled, and the control system 16-5 controls the manipulation light in the laser system 16-2 to perform coherent manipulation on the quantum state of the ions through the laser transmission device 16-2-1. After the operation is completed, the detection light emitted by the laser system 16-2 and the detection device 16-4 measure the result of the operation on the quantum state.

[0089] Furthermore, it should be understood that in the description of this application, terms such as "first," "second," and "third" are used only for distinguishing purposes and should not be construed as indicating or implying relative importance or order. References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in still other embodiments" appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0090] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions conceived by those skilled in the art based on the technical solution disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A laser transmission device, wherein the laser transmission device is applied in an ion trap system, characterized in that, The laser transmission device includes a spatial mode converter and a diffraction element array, wherein the spatial mode converter and the diffraction element array are located in different planes in space; The spatial mode converter is used to irradiate the diffraction element array with multiple laser beams, so that each laser beam irradiates one diffraction element of the diffraction element array. The diffraction element array is used to independently irradiate the multiple laser beams to the corresponding ions in the ion chain. Some of the laser beams are not parallel to each other after passing through a column of diffraction elements in the diffraction element array that is perpendicular to the direction of the ion chain. Each laser beam after passing through the diffraction element array corresponds to one ion in the ion chain, and the ion chain is a one-dimensional long chain including multiple ions.

2. The laser transmission device according to claim 1, characterized in that, The device further includes a collimator array, wherein a plurality of collimators in the collimator array correspond one-to-one with a plurality of diffraction elements in the diffraction element array; The collimator array is used to collimate multiple laser beams transmitted through the fiber optic array and then illuminates the spatial mode converter with the collimated laser beams.

3. The laser transmission device according to claim 1 or 2, characterized in that, The diffraction element is a metasurface structure formed by multiple micro-nano units fabricated from dielectric materials.

4. The laser transmission device according to claim 3, characterized in that, In the diffraction element array, adjacent diffraction elements along the direction parallel to the ion chain share a common micro / nano unit.

5. The laser transmission device according to claim 2, characterized in that, The collimator array consists of multiple collimating lenses, each with a different focal length along a direction perpendicular to the ion chain.

6. The laser transmission device according to claim 2, characterized in that, The collimator array includes a grating coupler array or an end-face coupler array.

7. The laser transmission device according to claim 1 or 2, characterized in that, The spatial mode converter includes multiple confocal lenses; or The spatial mode converter is an optical waveguide array.

8. The laser transmission device according to claim 7, characterized in that, The optical waveguide is a tapered optical waveguide.

9. The laser transmission device according to claim 8, characterized in that, The tapered optical waveguide has an arc-shaped slope structure.

10. The laser transmission device according to claim 7, characterized in that, The device also includes a rectangular waveguide array for transmitting the multiple laser beams to the spatial mode converter.

11. The laser transmission device according to claim 1 or 2, characterized in that, The device is located in a vacuum chamber.

12. An ion trap system, characterized in that, It includes an optical fiber array and a laser transmission device as described in any one of claims 1-11, wherein a plurality of optical fibers in the optical fiber array correspond one-to-one with a plurality of diffraction elements in the diffraction element array.

13. The ion trap system according to claim 12, characterized in that, The optical fiber is a thermally expanded TEC optical fiber.

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